Ventilating machines



Feb. 21, 1967 R. E. w. MANLEY 3,304,939

VENTILATING MACHINES Filed Deo. 13. 1963 INVEN'f-on Pas-ee EbumwUE'vmmeTH Mfmey BW/w-f W United States Patent fifice 3,304,939 PatentedFeb. 21, 1967 3,304,939 VIENTILAr ING MACHBNES Roger Edward WentworthManley, Chorleywood, England, assignor to Blease Anaesthetic EquipmentLimited, Northwood, England Filed Dec. 13, 1963, Ser. No. 330,355 Ciaimspriority, application Great Britain, Dec. 17, 1962, 47,546/ 62 4 Claims.(Cl. 128-1457) The present invention relates to ventilation machines andparticularly to portable ventilation machines by means of which oxygencan be supplied lthrough a breathing mask to a patient.

It is known for workmen engaged in cleaning out tanks or othercontainers for fuels or other substances giving otf fumes or vapourwhich is unable to support respiration or is otherwise harmful, to betrapped by pockets of the vapour or fumes and be rendered unconsciousbefore they are able to don a breathing mask or like apparatus. Minersin coal and other mines are exposed to like dangers. Known ventilationmachines Iare of no use in such circumstances in that they are notportable or have a plurality of independently adjustable controlsrequiring the use of a skilled operator before the machine is able tosupply gas of the required tidal volume and cycling rate to a patientconnected to the machine. Thus the use of such machines in a fuel tankor -other surroundings, as described above, is undesirable.

Accordingly the present invention aims at providing a portableventilation machine which automatically cycles gas at a preset tidalvolume and cycling rate when externally supplied with gas, and which hasno externally adjustable controls.

Accordingly the present invention provides a ventilation machinedesigned to be supplied with gas at a preset minute volume and to supplyit to a patient at a preset tidal volumewand Cycling rate, andincorporating means to supply gas to the patient regardless of theposition of the machine in its operating cycle when the patient appliesnegative pressure to the outlet of the machine.

By negative pressure throughout this specification is meant asub-atmospheric pressure such as is applied when a patient attempts toinhale gas issuing from the outlet of the machine at a rate faster thanthe machine is supplying gas to the outlet.

In a modification of the present invention the machine incorporates a`signalling device, such as a Whistle, connected through a biassedone-way or blow-off valve to the machine so that when a respiratoryobstruction occurs at the outlet of the machine, gas pressure in themachine rises to such a value that the one-way valve opens and causesthe gas pressure itself to operate the signalling device. The signallingdevice thus enables malfunctoning of the machine or a condition of thepatient requiring treatment, to be signalled.

The machine of the present invention may be self-contained, beingconnected to a replaceable and portable reservoir or cylinder of gasunder pressure, this being carried on or by the body of the machine, orthe machine may be designed to be connected to a supply line for gas athigh pressure.

The drawing consists of a partially diagrammatic figure of the machineaccording to the present invention.

The machine includes a housing for bellows 12 having flexible walls 14and an end plate 16. The end of the ellows opposite to the end plate 16is fixed to any convenient structural member 18 of the machine. Apivoted lever 20 is secured to the end plate 16, and this lever is urgedabout its fulcrum 22 by resilient means such as a compression spring 24in a direction tending to reduce the volume of the bellows 12. Themachine has a supply line 26 for gas at high pressure, e.g. 60 lbs.p.s.i.; gas from the line 26 passes through a pressure reduction valve28 and a preset needle valve 30. In the pressure reduction valve 28 thegas pressure is reduced, for example, to 5 lbs. p.s.i. and the needlevalve 30 is adjusted and preset to give a desired minute volume, e.g. 10litres per minute.

Gas leaves the bellows 12 through an outlet valve 32 operated by anover-centre mechanism 34 connected to the lever 20. The over-centremechanism 34 comprises a lever 36 pivotally mounted on a support 37attached to the structural member 18. The lever 36 is connected to thevalve member 38 of the valve 32 and to a lever 40 by a tension spring42. The lever 40 is pivoted on a support 44 secured to member 18, andits end opposite to that connected to the spring 42 is pivotallyconnected to a link 46 whose other end is connected to the biassed andpivoted lever 20. The link 46 has a longitudinal slot 47 ofpredetermined length, and the lever 20 has a pin 47a which projects intothis slot and transmits motion of the lever 20 to the link 46 when thepin 47a reaches the upper or lower end (as seen in the drawing) of theslot according to whether the lever 20 is moving anticlockwise orclockwise. This arrangement thus constitutes a lost-motion connectionbetween link 46 and lever 20. The operation of the over-centre mechanismis as follows. When the volume of the bellows is fairly large and theparts 20, 46, 42, 36, and 38 are as shown in the drawing, the force ofspring 42 acts in a direction tending to keep lever 36 in its extremeanti-clockwise position and the valve 32 therefore open. When thebellows contracts the lever 20 moves clockwise as seen in the drawing,and when the pin 47a reaches the lower end of the slot 47, the movementis transmitted to link 46 and the right hand end of the lever 40 movesupwardly as seen in the drawing. Eventually this pivoting of lever 36results in the toggle linkage comprising lever 40, spring 42, and lever36 passing its dead-centre or in-line position with the result that theforce of spring 42 acts in a direction .tending to urge lever 36 towardsits extreme clockwise position. This snap or toggle action results invalve 32 being closed. The continually -occurring inflow of gas viapressure reducing valve 28 and needle valve 30 then causes expansion ofthe bellows 12, and lever 20 consequently starts to move anticlockwise.The pin 47a therefore moves towards and into engagement with the upperend of the slot 47, as seen in the drawing, and the link 46 is thenmoved upwardly by continued expansion of the bellows 12. This pivotslever 40 in a clockwise direction past the toggle in-line position andsnaps valve 32 open again. It will thus be seen that the over-centremechanism 34 and associated parts function as automatic means whichautomatically and repeatedly carries out the cycle of opening Valve 32at a predetermined maximum volume of the bellows 12 to allow the bellowsto expel gas to the patient and closing valve 32 at a predeterminedsmaller volume of the bellows to allow the belows to be re-charged andthe patient to exhale. Further means to be described effect automaticactuation of an expiratory or exhaling valve 60 in sympathy with valve32.

From the outlet valve 32 the gas passes along a tu'be to a second presetneedle valve 48, and along a tube 51 to an outlet 50 designed to tbeconnected to the input limb 52 of a conventional breathing mask 54, ofwhich the output limb 56 is connected to a union 58. The latter isconnected to the expirat-ory valve 60 forming part of the machine. Theexpiratory valve 60 is of the biassed diaphragm type Controlled by gaspressure and is connected to the output side of the Outlet valve 32 ofthe bellows. The valve 60 has a diaphragm 62 bounding a space 64 andconnected to a valve member 66 which can close off the expirationoutlet. The valve 60 also has conventional non-return valve including a'ball 67 to prevent inhalation of the ambient atmosphere through theexhalation valve 60. The diaphragm 62 is :biassed by a spring 68 so thatwhen gas is passing through the outlet valve 32 the expiration valve 60is closed, the expiration valve 60 being opened When the pressure behindthe diaphragm, i.e. in the space 64, is less than the Outlet pressure ofthe bellows. Connected intermediate the second needle valve 4-8 and thetube 51 to the patients breathing mask 54 is a blow-off valve 70connected to a signaling device '73 such as a whistle. In this exampleof ventilation machine the bellows 12 are designed to be filled with gasat a pressure of 90 cms. of water, the expiration valve 60 to open at adifferential pressure of less than or equal to 60 cms. of water, and theblow-off valve 70 to open at a difierential pressure of 30 cms. ofwater.

Connected between the input to the blow-off valve 70 and the interior ofthe bellows 12 is a valve 72 connected to a biassed diaphragm 74 havingone side exposed to atmospheric pressure. The diaphragm valve 72 isbiassed shut 'by spring 76 when the pressure on the other side of thediaphragm is equal to or greater than atmospheric presusre. However whenthe pressure on said other side of the diaphragm becomes negative, asdefineid above, which happens by virtue of the connection between thediaphragm valve 72 and the outlet tube 51 to the patient, the diaphragmvalve 72 opens to permit gas to be expelled from the bellows 12 directlyto the patient under the action of the bias spring 24 of the bellows 12.Thus the diaphragm valve 72 acts as a spontaneous demand valve which isoperated whenever the patient attempts to inhale.

Connected intermediate the pressure reduction valve 28 and the firstneedle valve 30 is a passageway 78 leading to a lift valve 80communicating with the interior of the bellows 12. The plate 16 of the'bellows 12 is arranged to contact a movable member 82 of the lift valve80 so that when the bellows defiate further than the normal minimumvolume at 'which the outlet valve closes by action 'of the over-centremechanism, the lift valve is opened against its biassing spring 84. Whenthis happens gas passing through the pressure reduction valve 28 passesdirectly to the interior of the bellows 12, thus 'by-passing the firstneedle valve 30.

The pressure reduction valve 28 can be of any convenient knownconstruction, and since the precise details of such a valve form no partof the novelty 'of the present invention, the valve will not bedescribed. The needle valves 30 and 48 can take any form which will givea reasona'bly constant rate of fiow for a given substantially fixedinput pressure, and a convenient construction has been found to be ablock 'of metal with a small cylindrical hole drilled therethrough.Again, however, the precise construction of such fiow regulators formsno part of the invention.

The operation of the machine is as follows:

Gas, such as oxygen, passes at high pressure to the pressure reductionvalve 28 and issues therefrom at a pressure of about lbs. p.s.i. Fromthe pressure reduction valve 28 the gas passes through the first needlevalve 30 to the interior of the bellows 12 at a minute volume determinedaccurately by the setting of the first needle valve 30. When thepressure of gas in the bellows reaches and exceeds the pressurecorresponding to the bias on the lever of the bellows, e.g. 90 lbs.p.s.i., the |bellows inate, it being assumed that at this stage of thecycle the bellows are at or near their normal minimum volume positionwith the outlet valve 32 closed. When a volume of gas corresponding to apreset tidal volume, eg. 500 mls., has entered the bellows theover-centre mechanism operates to open the bellows outlet valve. Gas isimmediately supplied to the inlet side of the second needle valve 48 andto space 64 of the expiratory valve 60. The action of the second needlevalve is to control the rate at which gas fiows from the bellows 12 tothe patient, who is unable to breathe out because the expiratory valve60 is closed.

The inspiration phase of the breathing cycle is brought to an end whenthe lbellows reach their normal minimum position, at which the outletvalve 32 closes and the liftoff valve S0 is not operated. As soon as theoutlet valve closes the pressure on the inlet side of the second needlevalve 48 and in the control space 64 of the expirat'ory valve drops toenable the expiratory valve to open. The patient then exhales. While thepatient is so doing the bellows 12 are again being filled by theconstant supply of gas passing from supply line 26 to the lbellows 12.

As soon as the patient attempts to inhale, at a time when the bellowsoutlet valve 32 is closed, negative pressure is applied to one side ofthe diaphragm valve 72 to cause that valve to open. Thus gas already inthe bellows passes directly from the bellows to the patient via tube 51.Should the patient wish to inhale more gas than is immediately availablein the bellows the bellows descend through their normal minimum volumeposition to a position in which the lift-off valve 80 is opened.Thereafter, until the lift-off valve is again closed, gas passesdirectly via the outlet of the pressure reduction valve 28, the lift-offvalve 80, the bellows 12 and the diaphragm valve 72 to the patient. Assoon as the patient stops breathing in, the diaphragm valve 72 closesand the bellows 12 start to inflate, thereby closing the lift-off valve80 and re-establishing the automatic cycling of the machine.

Should the patienfs respiratory needs be smaller than those which themachine is adjusted to supply, as when a blockage occurs in the patienfslungs, the pressure on the outlet side of the second needle valve 48,when the bellows output valve 32 'is open, rises to the value of 30 cms.of water at which the blow-off valve opens, gas passing therethrough toa whistle or other signal device 73 to draw the attention of anattendant to the fact that the patient needs special attention.

In order to ensure that the patient is supplied with gas passing throughthe machine and not with gas drawn from the surro'unding atmosphere, theexpiratory valve incorporates a non-return valve 67 so that when thepatient attempts to inhale he has to draw in his gas from the outlet 50of the machine and not 'be reversing the direction of gas flow throughthe expirat'ory valve 60.

Thus it will be seen that the present invention provides an open-Circuitventilation machine having a valuable dual facility coupled withsubstantially fully automatic operation and no need for externaladjustment. Firstly the machine is adapted to supply gas at a minutevolume and a tidal volume sufficient -to ventilate normally an adult ofaverage body weight, providing the machine is supplied, to the pipe 26,With the appropriate gas; and secondly the machine 'can respondautomatically to spontaneous attempts to breathe by the patientconnected to the machine. The patient so attempting to breathe is freelysupplied with fully sufiicient quantities of gas by virtue of theby-passing of fiow regulator 30 through valve 80, and under thesecircumstances the automatic operation of the bellows 12 is over-ridden.

I claim:

1. A ventilation machine for supplying gas to a user comprising: avariable volume bellows; gas supply means comprising a pressure reducingvalve having an output port in series with a fiow regulator for feedinggas at a preset pressure and volume rate to the bellows; a first outletvalve for the bellows; an overcenter mechanism arranged to open theoutlet valve when the volume of the bellows exceeds a firstpredetermined value and to close the outlet valve when the volume of thebellows falls below a second predetermined value; a tube connecting theoutlet valve to a breathing mask for the user; a fluid pressureresponsive valve constituting a second outlet valve for the bellows andlocated in a path for gas that is in parallel with at least a portion ofthe said tube a'nd connected thereto, means opening said second outletvalve when the pressure applied by the user to the second outlet valveis a negative pressure; and a further valve which constitutes an inletvalve for the bellows and is connected to the gas supply means betweenthe output port yof the pressure reducing valve and the said flowregulator, means responsive to a contraction of the bellows beyond thesaid second predetermined value consequent upon the application of saidnegative pressure by the user of the machine, -for opening said lastnamed inlet valve.

2. A machine according to claim 1 comprising -an expi-ratory valvehaving a pressure-operated valve mem- -ber responsive to the pressure ina control space of the expiratory valve, and comprising conduit meansarranged to place the said control space in communication with theinterior of the bellows.

3. A machine according to olairn 1 comprising a blowoff valve connectedto the said tube, and a signalling device in series with said blow-offvalve, whereby in operation a use in pressure due to obstruction of thepatient's Ibreath-ng opens the blow-off valve and actuates thesignalling device.

4. A ventilation machine for supplying gas to a user comprising: avariable volume bellows; gas supply means comprising a pressure reducingvalve having an output port in series with a flow regulator for feedinggas at a preset pressure and volume rate to the bellows; a first outletvalve for the bellows; an overcenter mechanism arranged to open theoutlet valve when the volume of the bellows exceeds a firstpredeter-mined value and to close the outlet valve when the volume ofthe bellows falls below a second predetermined value thereby inoperation instituting a cyclic expansion and contraction of the bellows;a fluid pressure responsive valve constituting a second outlet valve forthe bellows, a tube connecting said second outlet valve to a mask forthe user and means opening said second outlet valve when the pressureapplied by the user in said tube is a negative pressure, the opening ofthe said second outlet valve acting to interrupt the said cyclicoperation of the bellows to allow the user to inhale.

References Cited by the Examiner UNITED STATES PATENTS 2,383,181 8/1945Enslin et al 128 29 2,871,854 2/1959 Lambertsen 128-142 2,900,977 8/1959 Marsh 128-142 3,046,979 7/1962 Andreasen 128-29 FOREIGN PATENTS1,218,838 5/ 1960 France.

842,890 7/1960 Great Britain.

908,874 10/ 1962 Great Britain.

OTHER REFERENCES British Journal of Anaesthesia, 1958, 30, 32, pp.32-36, .T R. Greer et all.

ROBERT E. MORGAN, Actng Primary Examner. C. F. ROSENBAUM, AssistantExaminer.

1. A VENTILATION MACHINE FOR SUPPLYING GAS TO A USER COMPRISING: AVARIABLE VOLUME BELLOWS; GAS SUPPLY MEANS COMPRISING A PRESSURE REDUCINGVALVE HAVING AN OUTPUT PORT IN SERIES WITH A FLOW REGULATOR FOR FEEDINGGAS AT A PRESET PRESSURE AND VOLUME RATE TO THE BELLOWS; A FIRST OUTLETVALVE FOR THE BELLOWS; AN OVERCENTER MECHANISM ARRANGED TO OPEN THEOUTLET VALVE WHEN THE VOLUME OF THE BELLOWS EXCEEDS A FIRSTPREDETERMINED VALUE AND TO CLOSE THE OUTLET VALVE WHEN THE VOLUME OF THEBELLOWS FALLS BELOW A SECOND PREDETERMINED VALUE; A TUBE CONNECTING THEOUTLET VALVE TO A BREATHING MASK FOR THE USER; A FLUID PRESSURERESPONSIVE VALVE CONSTITUTING A SECOND OUTLET VALVE FOR THE BELLOWS ANDLOCATED IN A PATH FOR GAS THAT IS IN PARALLEL WITH AT LEAST A PORTION OFTHE SAID TUBE AND CONNECTED THERETO, MEANS OPENING SAID SECOND OUTLETVALVE WHEN THE PRESSURE APPLIED BY THE USER TO THE SECOND OUTLET VALVEIS A NEGATIVE PRESSURE; AND A FURTHER VALVE WHICH CONSTITUTES AN INLETVALVE FOR THE BELLOWS AND IS CONNECTED TO THE GAS SUPPLY MEANS BETWEENTHE OUTPUT PORT OF THE PRESSURE REDUCING VALVE AND THE SAID FLOWREGULATOR, MEANS RESPONSIVE TO A CONTRACTION OF THE BELLOWS BEYOND THESAID SECOND PREDETERMINED VALUE CONSEQUENT UPON THE APPLICATION OF SAIDNEGATIVE PRESSURE BY THE USER OF THE MACHINE, FOR OPENING SAID LASTNAMED INLET VALVE.